Add date utils from timeline project

Author: dargaCode

src/utils/dateConstants.ts

@@ -1 +1,2 @@
 export const DATE_FORMAT = "YYYY-MM-DD";
+export const DATE_FORMAT_YEAR = "YYYY";

src/utils/dateUtils.test.ts

@@ -0,0 +1,70 @@
+import {
+  DATE_A,
+  DATE_A_NEXT_DAY_STRING,
+  INCLUSIVE_DATE_RANGE_A_TO_B,
+  DATE_A_TEN_SEQUENTIAL_DAYS_STRINGS,
+  DATE_B
+} from "./mockDateUtilsData";
+import {
+  getOneDayAfter,
+  getNSequentialDaysFromStart,
+  getDateRangeInclusiveDayCount,
+  isDateRangeValid
+} from "./dateUtils";
+import { DATE_FORMAT } from "./dateConstants";
+
+describe("dateUtils", () => {
+  describe("getOneDateAfter", () => {
+    it("should return the next day", () => {
+      const tomorrow = getOneDayAfter(DATE_A);
+
+      expect(tomorrow.format(DATE_FORMAT)).toBe(DATE_A_NEXT_DAY_STRING);
+    });
+  });
+
+  describe("getNSequentialDaysFromStart", () => {
+    it("should return an array of moments with the specified length", () => {
+      const dates = getNSequentialDaysFromStart(DATE_A, 10);
+
+      expect(dates).toHaveLength(DATE_A_TEN_SEQUENTIAL_DAYS_STRINGS.length);
+    });
+
+    it("should return an array of the correct sequential dates", () => {
+      const dates = getNSequentialDaysFromStart(DATE_A, 10);
+
+      dates.forEach((date, i) => {
+        expect(date.format(DATE_FORMAT)).toBe(
+          DATE_A_TEN_SEQUENTIAL_DAYS_STRINGS[i]
+        );
+      });
+    });
+  });
+
+  describe("getDateRangeInclusiveDayCount", () => {
+    it("should return the diff between start and end dates, plus 1", () => {
+      const range = getDateRangeInclusiveDayCount(DATE_A, DATE_B);
+
+      expect(range).toBe(INCLUSIVE_DATE_RANGE_A_TO_B);
+    });
+  });
+
+  describe("isDateRangeValid", () => {
+    describe("when startDate is after endDate", () => {
+      it("should return false", () => {
+        expect(isDateRangeValid(DATE_B, DATE_A)).toBe(false);
+      });
+    });
+
+    describe("when startDate is before endDate", () => {
+      it("should return true", () => {
+        expect(isDateRangeValid(DATE_A, DATE_B)).toBe(true);
+      });
+    });
+
+    describe("when startDate the same as endDate", () => {
+      it("should return true", () => {
+        expect(isDateRangeValid(DATE_A, DATE_A)).toBe(true);
+      });
+    });
+  });
+});

src/utils/dateUtils.ts

@@ -0,0 +1,55 @@
+import moment from "moment";
+
+export function getOneDayAfter(date: moment.Moment): moment.Moment {
+  return date.clone().add(1, "day");
+}
+
+/**
+ * return moments for the start date and n-1 sequential
+ * days after that. Sequence is every day, no gaps.
+ *
+ * @param startDate day to start counting from
+ * @param dayCount how many days to return total
+ */
+export function getNSequentialDaysFromStart(
+  startDate: moment.Moment,
+  dayCount: number
+): moment.Moment[] {
+  const dates: moment.Moment[] = [];
+  const currentDate = startDate.clone();
+
+  for (let i = 0; i < dayCount; i++) {
+    const date = currentDate.clone();
+
+    dates.push(date);
+    currentDate.add(1, "days");
+  }
+
+  return dates;
+}
+
+/**
+ * returns the total days between start and end date, inclusive
+ * of both the start date and end date
+ * @param startDate from the beginning of this day
+ * @param endDate to the end of this day
+ */
+export function getDateRangeInclusiveDayCount(
+  startDate: moment.Moment,
+  endDate: moment.Moment
+): number | undefined {
+  // inclusive of both start and end dates
+  return 1 + endDate.diff(startDate, "days");
+}
+
+/**
+ * return false if the end is before the beginning
+ * @param startDate
+ * @param endDate
+ */
+export function isDateRangeValid(
+  startDate: moment.Moment,
+  endDate: moment.Moment
+): boolean {
+  return endDate.isSameOrAfter(startDate);
+}

src/utils/mockDateUtilsData.ts

@@ -0,0 +1,23 @@
+import moment from "moment";
+import { DATE_FORMAT } from "./dateConstants";
+
+export const DATE_A = moment("2018-01-01", DATE_FORMAT);
+
+export const DATE_A_NEXT_DAY_STRING = "2018-01-02";
+
+export const DATE_B = moment("2018-01-10", DATE_FORMAT);
+
+export const INCLUSIVE_DATE_RANGE_A_TO_B = 10;
+
+export const DATE_A_TEN_SEQUENTIAL_DAYS_STRINGS = [
+  "2018-01-01",
+  "2018-01-02",
+  "2018-01-03",
+  "2018-01-04",
+  "2018-01-05",
+  "2018-01-06",
+  "2018-01-07",
+  "2018-01-08",
+  "2018-01-09",
+  "2018-01-10"
+];